1. Field of the Invention
The present invention relates to a treatment instrument for an endoscope, and more particularly to a treatment instrument for an endoscope that is used in endoscopic submucosal dissection (ESD).
2. Description of the Related Art
Endoscopic mucosal resection is recognized as a minimally invasive and reliable treatment that is useful as a radical operation for neoplastic mucosal lesions such as early esophageal cancer, early gastric cancer and early colorectal cancer. In recent years, a method referred to as endoscopic submucosal dissection (ESD) has been developed and brought into widespread use as a method that applies endoscopic mucosal resection to enable reliable en bloc resection of a lesion that extends over a wider area. In this method, en bloc resection of neoplastic mucosa is performed by cleaving submucosa between the mucosa and muscularis propria, after dissection of peritumoral mucosa.
International Patent Publication Nos. WO 2007/034708 A1 and WO 2008/026689 A1 disclose a treatment instrument for an endoscope that is used for endoscopic submucosal dissection (ESD).
A treatment instrument for an endoscope disclosed in FIG. 1 of International Patent Publication No. WO 2007/034708 A1 comprises a hand-side operation portion and an insertion portion that is connected to the hand-side operation portion. The insertion portion comprises a non-conductive cylindrical flexible sheath, an conductive wire that is passed through inside of the sheath, and a distal end electrode portion that is attached to a distal end portion of the sheath and is connected to a distal end portion of the wire. A proximal end portion of the wire is connected to a connector provided in the hand-side operation portion, and the connector is connected to a high-frequency current supply device.
Further, a treatment instrument for an endoscope disclosed in FIG. 28 of International Patent Publication No. WO 2008/026689 A1 comprises a hand-side operation portion and an insertion portion that is connected to the hand-side operation portion. The insertion portion comprises a non-conductive cylindrical flexible sheath, an conductive wire that is passed through inside of the sheath, an axial electrode that is protruded from or retracted into the distal end portion of the sheath by an operation of the hand-side operation portion and is connected to the distal end portion of the wire, and a distal end electrode portion that is connected to the distal end portion of the axial electrode. The proximal end portion of the wire is connected to a connector provided in the hand-side operation portion, and a high-frequency current supply device is connected to the connector.
Each of the aforementioned treatment instruments for an endoscope is inserted into a forceps channel that is arranged so as to pass through the endoscope insertion portion, and a distal end portion of the sheath protrudes from a forceps opening formed in a distal end rigid portion of the endoscope insertion portion. A surgeon operates the hand-side operation portion while observing an image from an image pickup portion provided at the distal end rigid portion to operate the distal end electrode portion to resect mucosa at a treatment site. Further, the treatment instrument for an endoscope disclosed in International Patent Publication No. WO 2008/026689 A1 can also dissect mucosa using the axial electrode by passing a high frequency current to the axial electrode.